Verrucaria striatula
Description : Thallus variable grass-green to dark-green, translucent when wet, subgelatinous, developing black spots which coalesce to form glossy, branched and swollen ridges (jugae) 100–200 μm wide, sometimes obscuring green tissue and making thallus appear black; jugae more strongly developed in sunny, open situations. Perithecia to 0.3 mm diam., sessile, becoming excavate to one side with age, the ostioles large. Involucrellum dimidiate to subentire, closely attached to exciple, extending a little at base. Exciple pale at base. Ascospores 7–11 × 4–7 μm.
S: Otago (Blackhead Dunedin, Taieri Mouth, S Taieri Beach), Southland (Howell's Point). On rocks in the upper littoral zone of rocky shores. Known also from Britain, Scandinavia, Iceland, the Atlantic coast of Europe and North America (Santesson 1939; Santesson et al. 2004; Elvebakk & Bjerke 2006). Australian collections are discussed by McCarthy (1991b: 327; 2001j: 193; 2003c).
Cosmopolitan
Illustrations : Zschacke (1934: 202, fig. 90); McCarthy (1991b: 331, fig. 8 I); Dobson (1992: 353; 2000: 403; 2005: 452); Flenniken & Gibson (2003: 44, 47, 48).
Verrucaria striatula is characterised by: the coastal rock habit; the variable grass-green (in shade) to dark-green (exposed to full sun), subgelatinous thallus, showing multiple black inclusions that form irregular ridges projecting above the surface (especially in sun-exposed habitats); large, glossy, conical perithecia that become irregular in shape through coalescing with thallus ridges; the involucrellum not extending laterally but extending downwards nearly to the base; exciple colourless at base; and small ascospores.
